There is a clear need to take urgent measures to stabilise the situation at the frontline, OSCE Secretary General Lamberto Zannier told reporters in Yerevan.
He expressed concern about the recent increase in incidents at the contact line between Armenian and Azerbaijani troops, Mediamax reported.
"Both sides should refrain from retaliatory action which would further exacerbate the situation," Lamberto Zannier said.
He stressed that parties should intensify their efforts to find a solution to the Nagorno-Karabakh conflict.
OSCE Secretary General also noted the need to build trust and to divert snipers from making contact and adopt a mechanism for investigating incidents.
The conflict between the two South Caucasus countries began in 1988 when Armenia made territorial claims against Azerbaijan. Armenian armed forces have occupied 20 per cent of Azerbaijan since 1992, including the Nagorno-Karabakh region and seven surrounding districts.
Azerbaijan and Armenia signed a ceasefire agreement in 1994. The co-chairs of the OSCE Minsk Group - Russia, France, and the U.S. - are currently holding the peace negotiations.
Armenia has not yet implemented the U.N. Security Council's four resolutions on the liberation of the Nagorno-Karabakh and the surrounding regions.